Directory (NR)

Has no indicators or subfield codes; the data elements are positionally defined.

Character Positions

00-02 - Tag
03-06 - Field length
07-11 - Starting character position

CHARACTER POSITION DEFINITION AND SCOPE

Computer-generated index to the location of the variable control and data fields within
a record. The Directory immediately follows the Leader at character position 24 and
consists of a series of fixed-length (12 character positions) entries that give the tag,
length, and starting character position of each variable field.

Field length and Starting character position portions of the Directory are defined by
Leader/20-23 (Entry map) as being 4 and 5 characters in length, respectively. Because a
field tag is always 3 characters, the length of the Tag portion of the Directory is not
specified in the Entry map.

DESCRIPTION OF A DIRECTORY ENTRY

■ CHARACTER POSITIONS

00-02 - Tag

Three ASCII numeric or ASCII alphabetic characters (uppercase or lowercase, but
not both) that identify an associated variable field.

03-06 - Field length

Four ASCII numeric characters that specify the length of the variable field to
which the entry corresponds. This length includes the indicators, subfield codes,
data, and the field terminator associated with the field. A Field length number of
less than four digits is right justified and unused positions contain zeros.

07-11 - Starting character position

Five ASCII numeric characters that specify the starting character position of the
variable field relative to the Base address of data (Leader/12-16) of the record.
A Starting character position number of less than five digits is right justified
and unused positions contain zeros.